While traveling with the Corps of Discovery across America's then-uncharted West, Sacagawea-with a baby strapped to her back-endured unimaginable dangers. We know little about her thoughts and feelings, since she left no records of her own, but without her, Lewis and Clark certainly could never have succeeded. Emma Carlson Berne separates truth from legend, and offers some ideas on what eventually happened to this strong and fascinating woman.